Up-regulation of CD44 variant exon expression in endometrial carcinomas: analysis of mRNA and protein isoforms, and relation to clinicopathological factors

Investigating the role of CD44 and hyaluronate in embryo-epithelial interaction using an in vitro model

Implantation failure is an important impediment to increasing success rates in assisted reproductive technologies. Knowledge of the cascade of morphological and molecular events at implantation remains limited. Cell surface CD44 and hyaluronate (HA) have been reported in the uterus, but a role in intercellular interaction at implantation remains to be evaluated. Mouse embryos were co-cultured with human Ishikawa endometrial epithelial monolayers over 2 days. Attachment was tenuous during the first 24 h, after which it became stable, leading to breaching of the monolayer. The effects of enzymatically reducing the density of HA, or introducing a function-blocking antibody to CD44, were monitored during progression from weak to stable embryonic attachment. Hyaluronidase-mediated removal of surface HA from the epithelial cells enhanced the speed of attachment, while a similar treatment of embryos had no effect. The antibody to CD44 caused retardation of initial attachment. These results suggest that CD44-HA binding could be employed by embryos during initial docking, but the persistence of HA in epithelial cells might be detrimental to later stages of implantation by retarding attainment of stable attachment.

CD44 variant overexpression in gallbladder carcinoma associated with tumor dedifferentiation

BACKGROUND

Recent studies have suggested a correlation between increased or decreased expression of CD44 variant molecules and tumor metastasis. CD44 expression in gallbladder carcinoma was examined and compared with tumor differentiation.

METHODS

Eighty-three samples of gallbladder carcinoma, 17 gallbladder adenoma samples, and 66 normal control mucosa samples were stained immunohistochemically for CD44 standard form (CD44s), variant 3 (CD44v3), and variant 6 (CD44v6). RNA extracted from nine patients with carcinoma also was investigated with reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and Southern blot hybridization (SBH) for the CD44 gene.

RESULTS

Normal gallbladder mucosa showed strong, membranous staining for CD44s but not for CD44v3 or CD44v6. In gallbladder tumors, CD44s was stained as strongly as it was in normal mucosa, but immunoreactivity for CD44v3 and CD44v6 also was significant. In well differentiated, advanced adenocarcinomas (n = 38), CD44s immunoreactivity was significantly lower in the invasive component than in the intramucosal component of the tumors (P = 0.0048). Immunoreactivity for CD44v3 and CD44v6 in moderately and poorly differentiated areas was significantly higher than in well differentiated areas (P < 0.0001 and P = 0.0378, respectively). RT-PCR and SBH signals for CD44v3 and CD44v6, including exons 7 and 10, were strong in carcinoma samples but weak in normal samples, in line with the results of immunohistochemistry. The prognosis of patients with gallbladder carcinoma was not associated significantly with altered expression of CD44s, CD44v3, or CD44v6.

CONCLUSIONS

The current study demonstrated that CD44 variant overexpression in patients with gallbladder carcinoma was linked closely with histologic dedifferentiation rather than clinicopathologic factors, including prognosis.

CD44 variant overexpression in gallbladder carcinoma associated with tumor dedifferentiation

BACKGROUND

Recent studies have suggested a correlation between increased or decreased expression of CD44 variant molecules and tumor metastasis. CD44 expression in gallbladder carcinoma was examined and compared with tumor differentiation.

METHODS

Eighty-three samples of gallbladder carcinoma, 17 gallbladder adenoma samples, and 66 normal control mucosa samples were stained immunohistochemically for CD44 standard form (CD44s), variant 3 (CD44v3), and variant 6 (CD44v6). RNA extracted from nine patients with carcinoma also was investigated with reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and Southern blot hybridization (SBH) for the CD44 gene.

RESULTS

Normal gallbladder mucosa showed strong, membranous staining for CD44s but not for CD44v3 or CD44v6. In gallbladder tumors, CD44s was stained as strongly as it was in normal mucosa, but immunoreactivity for CD44v3 and CD44v6 also was significant. In well differentiated, advanced adenocarcinomas (n = 38), CD44s immunoreactivity was significantly lower in the invasive component than in the intramucosal component of the tumors (P = 0.0048). Immunoreactivity for CD44v3 and CD44v6 in moderately and poorly differentiated areas was significantly higher than in well differentiated areas (P < 0.0001 and P = 0.0378, respectively). RT-PCR and SBH signals for CD44v3 and CD44v6, including exons 7 and 10, were strong in carcinoma samples but weak in normal samples, in line with the results of immunohistochemistry. The prognosis of patients with gallbladder carcinoma was not associated significantly with altered expression of CD44s, CD44v3, or CD44v6.

CONCLUSIONS

The current study demonstrated that CD44 variant overexpression in patients with gallbladder carcinoma was linked closely with histologic dedifferentiation rather than clinicopathologic factors, including prognosis.

Changes in expression of estrogen receptors alpha and beta in relation to progesterone receptor and pS2 status in normal and malignant endometrium

To clarify changes in estrogen receptor (ER) alpha and ERbeta during endometrial tumorigenesis, 48 endometrial carcinomas (endometrioid type), as well as 40 samples of normal endometrial tissue, were investigated using a combination of reverse-transcription and polymerase chain reaction with Southern blot hybridization and western blot assays, and the results were compared with findings for progesterone receptor (PR) and pS2 mRNA status. In addition, 166 carcinomas were also examined for immunohistochemistry, along with 171 normal specimens. Relative amounts of ERalpha at both mRNA and protein levels were significantly greater than those for ERbeta in normal and malignant endometrial lesions. ERalpha mRNA showed a stepwise decrease from normal or grade (G) 1 through to G3 tumor lesions, in line with changes in the protein levels, in contrast to ERbeta mRNA or protein expression, which did not alter, suggesting a shift in the ratio of the two ER subtypes during endometrial tumorigenesis. PR mRNA expression was significantly correlated with ERalpha, but not ERbeta mRNA status. Although significantly higher expression of pS2 mRNA or protein was observed in carcinomas than in the normal cases, there was no apparent association with the ER status. The findings suggest that alteration in estrogen signaling pathways may occur during endometrial tumorigenesis, and provide evidence that ERalpha expression may play an important role in the regulation of PR, but not pS2 expression in normal and malignant endometrium.

Expression of CD44 variants in lung cancer and its relationship to hyaluronan binding

We examined the expression of CD44 variant forms and their binding to hyaluronan (HA) in lung cancer cell lines. There was no relationship between the level of expression of CD44 variants and HA binding in different lung cancer cell lines. The expression of CD44v6 and CD44E in some cell lines was not always associated with HA binding. There was no relationship between the tissue pathological type and CD44 expression or HA binding. Deglycosylation by neuraminidase induced CD44-HA binding in human lung cancer cell lines. Our findings suggest that the HA binding ability of CD44, which is negatively regulated by glycosylation, might be a more important factor in tumorigenesis or metastasis than the expression of CD44 variant forms.

CD44 expression in benign, premalignant, and malignant ovarian neoplasms: relation to tumour development and progression

To clarify the possible role of CD44 expression in ovarian tumour development and progression, an immunohistochemical investigation was undertaken of a series of 115 carcinomas, 32 tumours with low malignant potential (LMP), and 53 cystadenomas. A combination of the reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot hybridization (SBH) assays was also performed for 17 malignant, four LMP, six cystadenoma, and seven normal ovarian samples. Immunoreactivity scores for CD44s, CD44v3, and CD44v6 were significantly higher in LMP and malignant tumours than in the benign or normal cases, in line with the results of gross mRNA-based assays. Exon-specific RT-PCR/SBH assays revealed that the expression of large CD44 transcripts containing v6 to v8 exons and small isoforms containing v2 and v3 was common among normal and neoplastic tissues, while a simultaneous increase of large isoforms containing v2 to v5 was also revealed in LMP and malignant tumours. In ovarian carcinomas, the scores for CD44s, CD44v3, and CD44v6 were inversely related to the FIGO stage, but there was no association with lymph node status or expression of hormone receptors. Multivariate analysis revealed loss of CD44v3 expression to be an independent factor for poor survival. The findings indicate that CD44 is up-regulated during the development of ovarian carcinomas but is subsequently down-regulated during their progression, resulting in aggressive behaviour and an unfavourable prognosis.